Devices for utilizing the energy in a current of water are of ancient origin and range from the mill wheel, used for grinding grain, to the hydro-electric generators which tap the energy of Niagara Falls. Useful energy has also been derived from currents of air by devices such as the windmill. The support frames for both the hydro-electric generator and the windmill are firmly anchored to the ground. Recently, the possibility of extracting energy from air currents has been explored by a number of inventors, as taught in U.S. Pat. Nos. 2,485,543; 2,784,556; 3,924,827 and 3,987,987. The last two patents are particularly interesting in that they disclose devices which are supported by air currents in the manner of kites. The significance of this feature will become evident in connection with the principal embodiment of the present invention.
A major disadvantage in attempting to utilize wind energy stems from the fact that the density of air is so low that considerable amounts of energy can be derived from air currents only by the use of impracticably large devices. However, the density of water is such that relatively small devices can provide substantial quantities of energy, provided the water velocity is of sufficient intensity.
Up to the present time, hydro-electric generators have been, for the most part, of the type in which the frame is anchored to the ground. Accordingly, such generators cannot readily take advantage of water currents such as in the middle of a stream, and cannot be adapted to take advantage of water currents where the direction of the current may vary with the time of day or with the tides. Accordingly, a hydro-electric generator which can adapt its position and orientation to the direction of flow of the water in which it is positioned and which can produce electricity at a high efficiency is greatly to be desired.